Rocket Power

The 1964 Oldsmobile 330-cubic-inch V-8

Feature Article from Hemmings Classic Car

The impact the fictional Hollywood character Buck Rogers and his flame-spitting spaceship had on the American public certainly was not overlooked by the marketing mavens in Lansing, Michigan.
America was on the cusp of the space age, and our society's passion for rocketry was carefully molded in Oldsmobile's business plan. In the fall of 1948, the first Oldsmobile engine marketed under the tag line of "Rocket Power" was introduced. The 303-cu.in. V-8 produced 135 horsepower and ushered in a new era of Oldsmobile's predominance in automotive engineering. By 1954, the displacement was increased to 324 cubic inches. This was accomplished without any major modifications to the basic architecture. In subsequent years, further increases in displacement were made possible by enlarging the bore and increasing the stroke until an engine of 394 cubic inches was created. When equipped with a four-barrel carburetor, the 394 V-8 produced 345 peak horsepower and, in many ways, was very similar to the 1949 model. The majority of external dimensions, bore centers, camshaft, distributor and oil pump location were not altered from the original version.
For the 1964 model year a new F-85 model was to be introduced, a slightly larger version of the compact Cutlass. Now considered an intermediate-sized car, V-8 power would be required as an option for the vehicle to gain the acceptance of the public. The Oldsmobile/Buick 215-cu.in. aluminum V-8 that was offered in the earlier compact version of the Cutlass was not up to the task of moving the heavier vehicle with the authority that eight cylinders under the hood suggested. After the preliminary engineering investigations were finished, it was decided that a new V-8 would be introduced along with the redesigned F-85. Designs with minimum deviations from the 394-cubic-inch V-8 were considered.
It soon became apparent that many of the fundamental dimensions of the 394 V-8 were perfectly suited to a smaller engine. The new F-85 engine was created to be 330 cubic inches, with a bore of 3.9375 inches and a stroke of 3.3850 inches. The cylinder block, cylinder heads and intake manifold were to be made of cast iron. Aluminum was to be employed for the pistons, water pump housing, water outlet, distributor housing, oil filter base, starter housing and the rocker arm shaft pedestals.
The Rocket 330 was destined to not only find its way under the hood of the F-85, but the full-sized Jetstar 88. It was necessary for the new engine to provide a good balance between performance and fuel economy. In the sporty F-85, performance would be further enhanced by the use of a higher compression ratio and a four-barrel carburetor. It was Oldsmobile's mandate that the new engine should also set benchmarks for reduced weight, cost and size while improving upon the company's already sterling reputation for quality. In addition, a high specific output per pound of weight and displacement was required of the design team.
Cylinder Block
The design of the cylinder block was critical to the project's success. An intense effort was extended to keep the block and the cylinder heads as small and light as possible. This was accomplished by designing the connecting rod as short as the crankcase geometry would permit and reducing the piston height to a minimum figure that was consistent with the ring land strength requirements.
The cylinder block was a fine-grain iron casting that required six cores to produce: three hot box cores and three baked sand cores. The timing chain cavity and the rear face were formed by baked sand cores. A feeder core of baked sand construction was used under the bulkheads for proper metal distribution.
The tapered holes in the cylinder bore cores were used to locate the water jacket cores. Conical projection on the water jacket core entered these conical holes and provided precise alignment of the water jacket, thus permitting thinner walls of uniform thickness on the casting. These locators were tied to the water jacket with four small sand sections around each bore, which produced four holes through the upper cylinder deck. During engine assembly, the holes were covered by the cylinder head and gasket, with some being left partially open for coolant circulation.
The water inlet hole at the front of the water jacket offered additional support to the core.
The lifter valley was cast solid except for one rectangular hole that was required to ventilate the crankcase. This design also increased the rigidity of the block. Seven oil drain holes were drilled at the lowest points in the valley. The cored cavity at the front was deep enough to permit a flat steel plate over the timing chain and fuel pump eccentric. This depth allowed the fuel pump to be mounted on the right front of the cylinder block. The oil filler tube was also located on the top of this extension.
The cored cavity at the rear of the block provided a flange for the attachment of the transmission and space for the distributor mounting.
Rotating Assembly
The crankshaft was forged steel, making it rigid and durable. The crankpins and counterweights were forged in position, thereby eliminating a twisting operation during manufacturing and reducing the cost of the finished product. The crankshaft thrust was taken by the center main bearing instead of the rear main bearing. This construction permitted flooding the thrust bearing with oil and reduced the rear main bearing slinger and seal requirements. Crankpin diameters and main bearing diameters were selected on the basis of bearing loads, crankshaft strength and endurance requirements. The main bearings were 2.50 inches and the crankpins were 2.12 inches in diameter. The engineered overlap in combination with robust cheek thickness provided a rigid crankshaft with very good torsional properties. It proved sufficiently rigid that a harmonic balancer was not required on the low-compression (9.00:1) Jetstar 88 engine. However, a harmonic balancer was employed on the high-compression (10.25:1) F-85 version. The balancer was necessary to maintain smooth engine operation at all speeds.
The main bearing fillets were rolled to secure an accurate shape and to increase fillet strength by cold working. Stress distribution was vastly improved due to the control of the fillet shape, something that would not be possible with grinding.
The goal of building a low-profile engine required that all components be kept as compact as possible. This resulted in a forged steel connecting rod that was only 6.00 inches long, center to center, as compared to a 6.625 inches long rod for the 1954 engine of comparable displacement. The new lightweight connecting rod reduced the amount of crankshaft counterweighting needed.
At the small end of the connecting rod, the bushing was eliminated by specifying a press fit piston pin. The piston bosses provided a large bearing area and eliminated a bearing clearance at the connecting rod small end, which resulted in a more rigid assembly. The pressed pin also eliminated the procedure to fit the bushing in place and machining it while eliminating the mandatory retaining rings.
The pistons were aluminum with cast-in steel struts for expansion control. The skirt was cam-ground to conform with the expansion characteristics of the piston. The height of the piston was kept to a minimum to meet Oldsmobile's need for a low-profile engine.
The piston ring spacing was reduced as much as possible while retaining proper land strength. The piston contour below the pin was designed to permit a large crankshaft counterweight radius.
This construction severely limited the skirt area and reduced the weight lugs to a minimum volume. The weight lugs proved to be ample enough to permit equalizing piston weight. Piston slap in a cold engine was effectively controlled by a piston pin offset of 0.06 inch. Compression ratio was controlled by using different depth dishes machined in the top of the piston head, rather than changing the combustion chamber volume. Dish volumes of 19.1cc and 5.3cc were employed, which produced compression ratios or 9.00:1 and 10.25:1, respectively.
Cylinder Heads
The right and left cylinder heads were identical iron castings. Ten head bolts of 7/16-inch diameter were used to attach the head to the block. Four bolts around each cylinder in a square pattern. In contrast, the 394-cu.in. V-8 used six bolts per cylinder bore. The four bolts used on the 330 V-8 are in the same location as four of the six used on the older engine, thus, tooling costs were reduced. The pushrod clearance holes were drilled rather than cast to secure maximum space for the intake ports. Three tapped holes were provided in each end of the cylinder head for the attachment of accessory brackets. The valve cover attached to the head with ten closely spaced 1/4-inch diameter bolts. A thin cork gasket was used to avoid distortion of the valve cover and the resultant oil leaks.
A unique intake and exhaust port arrangement was devised which contributed to the improved port shape and shorter exhaust manifolds. The intake and exhaust valves were reversed in each end cylinder from the usual arrangement. The exhaust manifolds were shorter as the exhaust ports of the two end cylinders were closer together. Each intake port was straighter and of more constant cross-section and did not share the space between two pushrods with another port. This construction permitted the use of straight rocker arms instead of offset rocker arms as are sometimes necessary to secure extra space for the intake port.
The combustion chamber was a low angle modified wedge design with a squish area opposite the spark plug to provide turbulence and decreased flame travel distance. The chamber roof angle of six degrees gave it a saucer-like shape. The valves were also on a six-degree angle; their centerline intersected the cylinder bore at the bottom face of the cylinder head, thereby ensuring a minimum of shrouding when the valves were open. The valve location along with the open chamber design resulted in a very free-breathing engine. The valve location also allowed the spark plug to be moved 0.4 inch closer to the centerline of the cylinder than in the 394 model. Thus, the distance from the spark plug to the most distant point in the chamber was reduced.
The placement of the spark plug provided for adequate cooling water. The space between the intake and exhaust valve was also generous for the same reason. The valve guides were cast integral with the cylinder head, which also simplified the transfer of heat to the coolant. Valve springs of conventional helical wound construction with a damper were used to control oscillation. The intake valve diameter was 1.875 inches and the exhaust valve diameter was 1.562 inches. The original intake valve head design was flat on top. However, dynamometer testing at Oldsmobile proved that a depression in the valve head actually lengthened its life. The new design allowed the valve head to conform to the valve seat in the cylinder head, thereby improving cooling and eliminating leakage. Hardened, malleable iron rocker arms operated on a solid steel shaft which cradled four die-cast aluminum half pedestals. The shaft was held in place by bolting through the shaft and the pedestal into the cylinder head. Light springs on the shaft held the rocker arms in position against the pedestals. Hollow pushrods actuated the rocker arms and supplied oil to the upper valve mechanism. The pushrods were 0.312 inch diameter steel tubing with drilled steel balls welded in the ends. The pushrod weight was 1.83 oz., which was 1.31 oz. less than the solid pushrods used on the 394 engine.
Camshaft
A hydraulic camshaft was required for quiet operation and no in-field service. The hydraulic lifters were 0.842-inch diameter and contained an oil metering system to feed lubricant to the pushrods. A flat metal disk floated in a restricted cavity below the pushrod seat. Oil pressure supported the disc in contact with a cylindrical seat. A small hole drilled through this cylindrical seat produced crescent-shaped slits through which oil was metered in controlled amounts.
The alloy cast camshaft had stepped bearing journal diameters which facilitated assembly in the cylinder block. The camshaft bearings were prefinished steel backed babbitt shell bearings pressed into the cylinder block. The cam was ground at an angle of 0 degrees, 9 minutes across the face, being slightly larger at the rear of each lobe. This angle, in contact with a spherical radius on the face of the lifter, produced a point of contact 0.10 inch from the centerline of the lifter. This offset in conjunction with the rotating camshaft caused the lifters to rotate and distribute the wear evenly across the face. The camshaft sprocket was an aluminum die-casting with nylon teeth.
The sprocket and fuel pump eccentric were held in place with one bolt. The camshaft was driven by a 1.2-inch pitch chain which was two links narrower than the chain specified for the 394-cubic-inch engine. The resulting 1/8-inch narrower chain saved space as well as material. The camshaft and crankshaft sprockets also benefited from this refinement.
Intake Manifold
The cast-iron intake manifold was a conventional dual-plane "H"- pattern with widespread ports made possible by the layout of the cylinder head. An exhaust crossover was provided to vaporize fuel on cold startup. Carburetor choke heat was arranged by a tube submerged in the exhaust crossover. At the front of the intake manifold, the water crossover collected coolant from each cylinder head, and at the center of the water crossover a cavity was provided for the thermostat.
Embossed steel gaskets were used between the intake manifold and the cylinder heads. Soft rubber gaskets absorbed the variation between the intake manifold and the cylinder block at each end.
Oil vapor and splash were deflected from the exhaust crossover by a sheetmetal baffle fastened to the cylinder block and closely fitted to the underside of the intake manifold.
This same basic intake manifold design was used with both two- and four-barrel versions of the engine, with only the necessary modifications made to accept the different carburetor.
A good design
The F-85 high-compression engine with the four-barrel carburetor produced 290 horsepower and 355-lbs.ft. of torque. Interestingly, Oldsmobile offered a high-compression two-barrel carburetor version that boasted 245 horsepower and 345-lbs.ft. of torque. The Jetstar 88 low-compression engine came only with a two-barrel carburetor and produced a healthy 230 horsepower and 325-lbs.ft. of torque. The torque curves of the two engines using two-barrel carburetors were parallel with the expectations of reduced thermal efficiency. Likewise, the torque curve of the four-barrel F-85 engine showed a substantial increase in the upper speed ranges. This was the result of the larger carburetor allowing the engine to take advantage of the good breathing cylinder heads.
The F-85 and Jetstar 88 engine were well received by the public and produced the results the engineers had aimed for. Good power, class leading fuel economy and reliability along with Oldsmobile smoothness.
Riding high on their success, the debut of the 330 engine was a proud milestone in Oldsmobile's history. Who would have thought that just 40 years later General Motors would put an end to the once-famous division by closing it down? That day in 2005 when the last Oldsmobile product rolled from an assembly line was a sad moment for America.

This article originally appeared in the June, 2006 issue of Hemmings Classic Car.